Synthesis and Chemical Properties of Dielectric Polyphenylenes with Nitro Group

Polyphenylenes consisting of nitrophenylene and didodecyloxy-p-phenylene units have been synthesized by Pd-catalyzed organometallic polycondensation. The polymers showed good solubility and had number-average molecular weights (M,,) of 13,000-37,000. Their spin-coated films showed fairly high dielectric constants (F) of 3.75-6.36. The polymers were electrochemically active with electrochemical reduction peaks in the range of -1.72 to -1.99 V versus Ag+/Ag in an acetonitrile solution of [NEt4]BF4 (0.10M). The polymer composed of 2,3'-dinitrobiphenyl and didodecyloxy-p-phenylene units showed thermotropic liquid crystalline phase at about 240 degrees C. Cast films of the polymer had a birefringent phase at room temperature, suggesting self-assembly of the polymer in the solid. XRD studies revealed that the polymers assumed an ordered structure assisted by aggregation of the long alkoxy side chains in the solid. The polymer main chain in the cast film is considered to be aligned parallel with respect to the surface of substrates. (c) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 2426-2435, 2009